Sectional overhead doors have been commonly employed for many years as garage doors in homes, commercial and utility building doors, and in similar applications. The panels of conventional sectional doors are commonly joined by hinges positioned on the inner or internal side of the door which form pivot points proximate the juncture between each of the adjacent panels to permit the panels to pivot relative to each other. The hinges at the lateral edges of the panels or separate mounting brackets carry shaft-mounted rollers which inter-engage with track sections that control the path of travel of the doors. These track systems commonly include a generally vertical section positioned proximate a door frame or other opening and a generally horizontal section that extends substantially perpendicular to the vertical section rearwardly into the interior of the building in an overhead position. A curved transition section is normally positioned proximate the header at the top of the door frame and interconnects the vertical section and the horizontal section to provide a continuous track system. The hinges permit the door panels to articulate as the rollers interconnecting the door and the track system traverse from the vertical section through the transition section to the horizontal section of the track and vice versa.
Hinges employed for such sectional overhead doors have remained of generally consistent design over many years. Most commonly the hinges have been stamped from relatively lightweight steel, with the formation of gussets and sidewalls to obtain the requisite strength. The two hinged leaves with the formed contours are normally attached at their knuckle areas by a pivot pin. The pivot pins are commonly a rolled pin formed of the same or a comparable light-gauge steel and flared at the end during assembly for retaining the pin in the knuckles. The hinge leaves may be provided with an additional roll pin supported in a flange and mounting guide rollers which engage the track sections. Hinges of this type tend to be relatively crude and are noted for binding and poor operation, at least after some operating period if not shortly after installation. Particularly troublesome in this respect is the lack of uniformity of the flaring of the rolled pivot pins, which is notoriously imprecise. Further, with the rolled pin configuration, the extreme lateral edges of the hinge material end up serving as the bearing surface between the hinges and the rolled pivot pin.
In some instances, sectional doors for certain applications have been made which employ interfitting cylindrical members at the edges of adjacent panels. Normally, these cylindrical members have constituted an extension of a wall or covering for the panels, which extend the entire lateral width of the panels. Each of the panel extensions are formed into a segment of a cylinder at a pivot joint, with one being radially slightly smaller than the other to interfit therein. Frequently, a tubular bearing member is inserted within the interfitting cylindrical members to serve as a hinge pin and to receive the shaft for a roller extending outwardly for engagement with a track positioned proximate to the door. Such interfitting cylindrical members, however, in extending the full length of the door, require a considerable amount of additional material at substantial cost. Additionally, hinges extending the full transverse width of a door panel, particularly in sizeable doors, are prone to binding and chafing over large surface areas of the cylindrical hinge members due to the inevitable bending or deflection which necessarily takes place over the substantial lateral extent or width of the cylindrical hinge members.
A recently significant consideration which is involved in the configuration and operation of the hinges and the interconnected panels is that of providing an anti-pinch characteristic. This refers to the provision of some type of structure to cover or minimize the gap formed between the panels, particularly at their position of maximum angularity when traversing the curved transition section of the interrelated track, such as to prevent the insertion of a person's hands or fingers whereby they could be pinched as the door moves between the track sections. In this respect, it has been empirically determined that a gap between the edges of adjacent panels during articulation of the door panels not exceeding approximately 0.2 in. or 5 mm. satisfies these requirements.
To date, various approaches have been taken to incorporate anti-pinch features to some extent into sectional overhead doors. One approach for providing an anti-pinch joint between adjacent panels of a sectional overhead door is to create an external barrier which is designed to preclude the entrance of a person's finger or other object into the hinge area. Anti-pinch devices of this type may be made of rigid or somewhat flexible materials and are characteristically attached to the outside of the door panels in proximity to the hinge area. For the most part, these barriers are formed or in some manner biased, as by a spring or otherwise, to maintain the barrier material in contact with the exterior surface of adjacent door panels throughout the pivotal action of the panels when traversing between the vertical and horizontal track sections. Such external barriers often require a substantial amount of material, as well as precise positioning and operation, to insure that the external barrier is maintained during the entirety of the angular movement which takes place between the panels. Flexible external barrier devices may be subject to damage or deterioration caused by weather conditions due to their outward, fully exposed positioning. As a result of these drawbacks, efforts have been made to provide anti-pinch devices which take a form other than an external barrier.
More recently, efforts have been made to construct what might be termed an internal barrier to accomplish an anti-pinch function. Doors of this type endeavor to provide contours on the mating edges of adjacent panels, such that an overlapping surface or a gap too narrow for the insertion of a person's finger is presented at all times during the angular rotation between adjacent panels from the smallest to the largest angular orientations for a particular sectional overhead door system.
Numerous problems, however, have been encountered in the application of an internal barrier configuration to overhead door panels. In some instances, intricate configurations are employed which may tend to cause very stringent fabrication requirements or unduly precise installation procedures. Any deficiencies in these respects normally result in door panels which minimally interfere or bind to a sufficient extent to cause highly undesirable drag in the movement of the door. In some instances, the contoured panel edges may be configured, such that it is difficult or impossible to effect the attachment of hinges at a sufficiently reinforced surface or at locations where the pivot axis of the hinges is optimally located. In other instances, the edge configurations make sealing against water and air filtration extremely difficult, if not impossible. Another problem with the use of contoured edges is that in many instances it is difficult to achieve a rapid separation of the interfitting surfaces as soon as an angularity between the panel commences to preclude the introduction of undesirable drag forces. To Applicants' knowledge, no internal barrier configuration has fully satisfied all these various competing requirements.
Sectional overhead doors also normally employ brackets rather than hinges to mount rollers proximate the upper edge of the top panel and proximate the lower edge of the bottom panel. The bottom bracket located proximate the lower edge of the bottom panel also serves the purpose of providing a connector for attachment of the counterbalancing system to the door. In particular, the bracket has an anchor for attachment of the end of the cable which interrelates with the tensioning elements, commonly springs, of the counterbalance system for the door. The brackets also normally have an attached cylindrical sleeve for receiving a shaft mounting a roller that is affixed to a mounting plate of the bracket, which is normally attached to the door by fasteners. The fasteners are normally located spaced from the cylindrical sleeve to permit easy access by tools for operating the fasteners.
This common arrangement can produce a significant safety hazard when installation and repair personnel or owners of buildings having such sectional overhead doors attempt to effect adjustment or replacement of damaged bottom bracket components. The problem from a safety vantage arises when a person endeavors to loosen or remove the bottom bracket from the door with the door in the closed, vertical position. Under this condition, the counterbalance system is exerting maximum force on the bottom bracket through the connecting cable. As a result, if the fasteners on the bottom bracket are removed or nearly removed, the counterbalance system operating through the connecting cable forces the entire bottom bracket upwardly at great force and speed causing the potential for serious injury to a person in close proximity endeavoring to remove the bracket. In many instances, persons working on an overhead door do not perceive the impending danger associated with removal of the bottom bracket in the closed, vertical position until the above-described dangerous result has taken place.
In recent years, panels for sectional overhead doors of the type described herein constructed of foam with a skin cover have enjoyed increasing popularity. Refinements in such door panels have come largely in terms of the materials or combinations of materials employed in the skin. While light-gage steel is commonly used for the outer skin exposed to the outdoor environment, less expensive materials, such as treated or metallic-coated paper and non-metallic sheet materials, are increasingly employed as inner skin coverings for selected applications. Efforts have also been made in foam compounding to develop less expensive foams having the required strength and insulation qualities. What has remained constant is the notion that a substantially uniform thickness of foam, whether precut inserts or expanded in place, is necessary to achieve required strength and insulation characteristics of panels having a foam core.
In a general sense, various apparatus for the production of conventional sectional overhead door panels has been developed in the industry. In some instances, pre-formed foam slabs have been cut to appropriate sizes and assembled by hand on conveyor lines with an outer skin, an inner skin, stiles, and one or more ribs or struts. In other instances, relatively high-speed, continuous production equipment has been developed to achieve substantially automated production of panels.
Existing continuous production equipment has normally been subject to a variety of relatively severe limitations and/or disadvantages. In order to achieve essentially automated production, it is necessary that foam be continuously dispensed within the skins of a moving panel at the time of or before forming the enclosed panels. It is, however, necessary during the expansion of the foam in an oven that the normally relatively thin skins forming the sides of the panel be supported, as by a conveyor surface moving at substantially the same velocity, to withstand the internal pressure created by the foam until it becomes substantially set. Both flat platen or slat conveyors and conventional roller conveyors may be employed in an oven to meet these requirements.
The use of flat platens and conventional roller conveyors has, for the most part, limited panel configurations to essentially rectangular shapes with substantially planar surfaces. The use of longitudinal reinforcing struts or ribs which are advantageously also interiorly foamed require corresponding recesses in the platens or rolls. However, it is often necessary, or at least desirable, to have different strut dimensions and locations for the three or four different panel sizes necessary to provide, for example, the several different standard door heights. To thus provide different platens or rollers for each panel size and type can result in an inordinate number of platens and rollers, considering that such conveyors commonly have many dozens of rollers. In addition, many hours of production time may be lost in changing the numerous platens or rollers each time a changeover is made to run a different panel. As a result, sectional overhead doors have tended to be relatively expensive and/or designed with significant structural compromises to maintain equipment costs and manual changeover expenses within permissible bounds.